Jeff Walden — Rename the current CharT typename parameter, used for either char16_t or mozilla::Utf8Unit, to Unit -- so that CharT can be used for actual C++ character types, when such are needed to intermesh with character-demanding APIs. Also change a few "chars" in function/variable names to "units" for consistency. No bug, rs=jorendorff over IRC

Jonathan Kew — Bug 1498316 - Limit the number of nsFontMetrics entries cached by each device context, to avoid excessive growth of this cache in examples such as animated font variations or sizes. r=lsalzman